Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.45	8.817%	$200.713	$200.71	$200.70	$200.70
Purchase #2	$192.54	3.770%	$199.7988	$199.80	$199.80	$199.80
Purchase #3	$214.84	12.513%	$241.7229	$241.72	$241.70	$241.70
Purchase #4	$144.27	5.550%	$152.277	$152.28	$152.30	$152.30
Purchase #5	$70.66	10.591%	$78.1436	$78.14	$78.15	$78.10
Purchase #6	$167.71	12.439%	$188.5714	$188.57	$188.55	$188.60
Purchase #7	$168.91	3.842%	$175.3995	$175.40	$175.40	$175.40
7 purchase totals =	$1,143.38		$1,236.6262	$1,236.62	$1,236.60	$1,236.60